UB Scientists Find That Nerve Cells 'prefer' to Grow On Teflon-Type Surface

BUFFALO, N.Y. -- University at Buffalo scientists and collaborators at other institutions working on substrates for nerve-tissue regeneration have developed new surface chemistry to create the first modified Teflon surface that controls how cells stick to it.

Eventually, the researchers say, the new surface chemistry could be part of a tissue-regeneration or wound-healing system that would help support, as well as direct, the growth of new neural tissue where existing tissue has been damaged.

The research, involving mouse cells from permanent cell lines, is described in two papers being published in this month's issue of the Journal of Biomedical Materials Research. A third paper on related research is in press at the Journal of Neuroscience Research.

The surface modification brings two key potential advantages to biomaterials: It allows scientists to attach nerve cells to a Teflon surface, a material of choice for biomaterials used today, and it lets them control where on the surface the cells will grow.

"We don't yet know why central-nervous-system tissue does not regenerate," said Joseph A. Gardella, Jr., Ph.D., professor of chemistry at the University at Buffalo and co-author of the papers.

"The idea is that something happens in the early developmental stages, some kind of biochemical switch that says don't grow there, grow here," he said. "In later stages of development, that switch turns off and we don't know how to turn it back on again."

Once neurobiologists isolate that switch, the new surface chemistry could incorporate it, eventually becoming an important substrate for biomedical implants. This is because the new surface chemistry developed at UB allows scientists to put cells down in precise patterns, a prerequisite for substrates that would be used to grow nerve cells.

"In order for neural tissue to regenerate, cells need to be positioned in a particular direction," explained Gardella.

He added that neural-cell biologists believe that if cells are not positioned properly on a surface, they won't transmit nerve signals as well.

"What was startling about our experiments is that in almost all cases, the nerve cells, which will stick to and grow on an unaltered Teflon surface, preferred instead to grow on our modified Teflon surface when exposed to it," he said. "The nerve cells made a definite choice between two different surface chemistries."

Even now, the surface chemistry provides a test surface for experiments exploring factors that contribute to the growth of neural cells on surfaces.

"Now we have a testbed for proteins or peptides that biologists believe may be part of the signaling process that tells neural cells where and how to grow," said Gardella. "And because the new surface provides a clear, simple and rapid way to test hypotheses, fewer animal tests will eventually be needed."

The researchers modify the Teflon surface by exposing it to a radio-frequency glow-discharge plasma. The plasma creates areas where hydroxyl groups -- a key ingredient in making things stick to Teflon -- become chemically reactive.

A specific minimal peptide sequence, a small piece of a protein known to encourage nerve cells to adhere to surfaces, is then covalently bound to the hydroxyls. This material is then exposed to the nerve cells from permanent cell lines for adhesion.

"With neural cells, the issue wasn't just, do they stick or not, but we had an opportunity to watch the cells grow and send out neurites once they had been attached," said Gardella. "Nerve cells have many stages of healthy growth, from adhesion to differentiation in the formation of neurites and axons. We have observed these right through the neurite stage."

The next step will be to test nerve cells from living animals and then humans.

Gardella co-authored the papers with Frank V. Bright, Ph.D., associate professor of chemistry at UB; E.J. Bekos, UB doctoral candidate in chemistry; researchers at the Centre Hospitalier Universitaire Vaudois in Switzerland, M.I.T. and Kodak Research Laboratories, and former UB postdoctoral associates Terrence G. Vargo and Y.S. Kim, now at the Naval Research Laboratory and the Korea Standards Research Institute, respectively.